1. Field of the Invention
The present general inventive concept relates to an apparatus to inspect a thin film transistor (TFT) substrate and a method of inspecting a TFT substrate, and more particularly, to an apparatus to inspect a TFT substrate and a method of inspecting a TFT substrate that measures an electric signal generated in a pixel electrode via a data line by irradiating the pixel electrode with an electron beam.
2. Description of the Related Art
An example of a flat panel display popularly used in recent years is a liquid crystal display (LCD). The LCD includes a TFT substrate where TFTs of a switching element are formed, a color filter substrate where color filter layers are formed, and a liquid crystal layer formed between both substrates.
The TFT substrate is formed by a multi-step photolithography method, and the TFT substrate is inspected after each step to decide whether the TFT substrate is defective or not. An electron beam is used for inspecting the TFT substrate having a pixel electrode connected to the TFT.
Conventionally, the electron beam is applied to the pixel electrode while a certain voltage is applied to the pixel electrode. For example, the electron beam is applied to the pixel electrode while a voltage of 5V is applied to the pixel electrode, and the degree of a secondary electron beam from the pixel electrode is measured. When the degree of the secondary electron beam from the pixel electrode is less than a predetermined value means, the pixel electrode is applied with less than 5V, and thus the TFT can be decided to be defective.
However, the conventional method needs an additional detector to measure the secondary electron beam from the pixel electrode and a configuration to apply the voltage to the pixel electrode becomes complex.